Turbine-blade bracing



FEB. 9

F. HODGKINSON TURBINE BLADE BRACING Filec'l May 22, 1925 WITNESSE EHodgkinson ATTORNEY INVENT OR 09m Patented Feb. 22, 1927.

NITED STATES PAT T FRANGISHODGKINSON, OF SWARTHMORE, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

TURBINE-BLADE snacmo.

Application filed May 22, 1925. Serial No. 32,151.

My invention relates to elastic fluid turbines, more particularly to the blading thereof, and has for its object the rovision I of an eificient bracing for the 'bla es which 8 shall be easy to apply, offer a minimum of resistance to the flow of elastic fluid through the turbine, establish a sturdy, unitary blading structure and which shall minimize vibration of the blades;

Apparatus embodying features of my invention is illustrated in the accompanying drawings forming a part of thisspecification, in which Fig. 1 1s a fragmentary plan View of a turbine blade carrying element, 16 either moving or stationary, with a plu-' rality of blades mounted thereon, said blades being provided with my improved blade bracing; Fig. 2 is a sectional view across a bracing member taken along the line II-II of Fi 1; Fig. 3 is a vertical sectional viewof t e blading shown in Fig. 1 along the line III-J11 thereof and showing the blades mounted upon a fragment of a-turbinerotor; Fig. 4 1s a'detached plan I view of thelashing members, and Fig. 5

shows a perspective view of a modified form of my invention.

As is well known in the art to which my invention. relates, turbine blades, in operaeo tion, are subjected to various shocks and strainswhich tend to cause vibration. It has been found necessary therefore to provide some form of bracing means in order to minimize vibration of the blades. Various forms of blade lashing have been proposed, that more commonly used being in the form ofya lashing wire which is threaded through holes in the blades and secured to i the blades either by deformin the wire where it passes through the b ade or by soldering or brazing the'wire to the blade where it passes through the hole. D1flicul-- ties have been encountered in securing a lashing wire to a blade by deformation of the .wire due to the fact that a thorough mechanical connection is hard to obtain by such means. On the other hand, brazing or soldering the lashing wire to the. blades tends to injure the physical properties of .50 the'blades and thus weakens them.

In accordance with my invention, I provide a bracing comprised of individual bracing members secured to the front and back of adjacent blades in a row, and join the individual members together at a point intermediate the blades. .The individual members are cut from bars of metal of stream line cross section in the direction of motive fluid flow and are each provided with one or more tenons adapted to pass through suitable holes in the blades and are riveted before assembly in the blade holding element. The individual members may be joined together between the blades by fusion of metal, preferably welding. The welding operation, being carried out at a point remote from the blades, does not materially heat the blades and thus has no deleterious effect upon the physical properties of the blades.

Individual members are secured to the front and back of a blade in staggered relation, thus bracing the blade at two points of its length for each row of lashing and further minimizing the vibration of the blade. I

Referring now to the drawings for a better understanding of my invention, I

of two members 12 and 13 so cut that wheneach is riveted to its associated blade and the two joined together they form a member rigidly securing the one blade to the other. The form in which the members are cut is best seen by reference to Figs. 4 and 5.

The inner end, or end adjacent the blades, of each of the lashing members 12 and 13 is cut to conform to the contour of the blade to which it is attached. Each of the pieces 12 and 13 is provided with one or more tenons 15 and 16 adapted to pass through complementary holes 17 and 18 formed in the blades 11. The outer ends of each of the members 12 and 13, or ends remote from the blading, are beveled as shown at 19 and 21 in Figs. 3 and 4 to provide a better means for joining the edges upon assembl by fusion of metal, such as by soldering, razing or weldin The bracing members 12 and 13 are stream line 1n cross section as shown in Fig. 2 so as to. offer the minimum resistance to flow of the motive fluid therethrough.

In assembling the blading structure, the members 12 and 13 are fitted to the blades and the ends of the tenons 15 and 16 riveted, thus firmly securing the members to the blades. Holes 17 and holes 18 are provided in each of the blades, one set below the other, so that members 12 and 13 for each blade are in staggered relation to each other. The blades are then assembled in the blade holding element and adjacent ends of the elements 12 and 13 are joined together by Welding or other similar process, thus forming a unitary structure of the whole.

As is well understood, blade lashing is usually applied to segments of blades around the blade carrying element in order to avoid diliiculties due to unequal expansion and contraction of the parts. In Fig.

3 I show, for the purpose of illustration, a

segment of tour blades thus united, though the number of blades in a segment will depend entirely upon their physical characteristics and the service to which they are subjected. It will be clearly understood from the drawing that by carrying out the welding process employed in joining the individual lashing members together remotely from the blades, the heat thereof does not atl'ect the physical properties of the blades. It may be further seen that the staggered relation of the lashing members, as applied to a blade. permits an expansion thereof between the bladcs without danger of crushing or weakening the material of which the lashing members is composed.

Referring to Fig. 5 I show a modified form of my invention wherein the bracing member 12 is provided with only one tenon, 21. The tenon 21 is made angular in crosssection and is adapted to tit into a hole of similar contour formed in the blade. The purpose of the angular formation of the tenon :31 is to prevent the bracing member 12 from turning at'ter assembly in the turbine.

From the foregoing. it. will be apparent that I have invented an improved bracing means to! turbine blades which otl'crs a minimmn of resistance to the (low of motive fluid through -the blades, which is easy ol assembly, which may be assembled without .all'ccting the physical properties of the blades and which provides a sturdy unitary blade structure.

\Vhile I have shown my invention in but modifications. without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

What I claim is: j

1. A turbine blade bracing means comprising a plurality of bracing members disposed between adjacent blades, said bracing members being secured to the adjacent blades and joined to each other intermediate said adjacent blades.

2. In a turbine, a plurality of blades in a row. a bracing member secured to each of the blades and joined to the bracing member of an adjacent blade by fusion of metal intermediate said adjacent blades.

3. In a turbine, a plurality of blades in .a row a bracing member secured to the front and a bracing member secured to the back of each of the blades, each of said bracing members being secured to the bracing member of an adjacent blade at a point intermediate the adjacent blades.

4. In a turbine, a plurality of blades in a row, a bracing member secured to the front and a bracing member secured to the back of each of the blades in staggered relation, each of said bracing members being secured to the bracing member of an adjacent blade at a point intermediate the adjacent blades by fusion of metal.

In a turbine, a ,blade carrying element, a blade mounted in said element, a bracing member for the blade, said bracing member comprising a strip of metal of stream line cross section having one or more tenons thereon for riveting to the blade and joined to an adjacent bracing member by fusion of metal.

(3. In a turbine, a blade carrying element, a blade mounted in said element, a bracing member for the blade, said bracing member comprising a strip of metal of stream line cross section having one or more tenons thereon for riveting to the blade and having its outer end bevelled and joined to an adjacent bracing member by fusion of metal.

7. In a turbine, a blade carrying element, a blade mounted thereon, a pair of bracing members for the blade extending across the trout and back thereof in otl'set relation, eachot said bracing members comprising a piece oi? metal of stream line cross section in the direction of motive tluid flow and cut to conform to the contour of the blade,holes provldcd in the blade. tenons provided on the bracing mcmbcl's and fitting into the holes tor riveting to the blade. said pieces of metal being bevelled at their outer ends tor joining to an adjacent bracing member.

8. In a turbine. a plurality of blades in a row. a member secured to the trout face and a member secured to the back face of each of the blades and adjacent members being adjacent members being Welded together injoined intermediately of the spaces between termediately of the spaces between blades. blades. In testimony whereof, I have hereunto 10 9. In a turbine, a plurality of blades in subscribed my name this 29th day of April, 5. a row, a member secured to the front face 1925.

and a member secured to the back face of each of the blades in ofl'set relation and- FRANCIS HODGKINSON. 

